The present invention relates generally to catheters for radiation therapy and to connectors and systems for use with such catheters.
Loss of normal control of cellular proliferation results in unregulated cell growth and, often, the formation of cellular masses commonly known as tumors. Tumors may be malignant or non-malignant. The cells of malignant tumors often exhibit a lack of normal differentiation and possess the ability to invade local tissues and metastasize, whereas, in non-malignant tumors, the mass of cells is generally localized. Malignant tumors can develop in any organ at any age and, even with treatment, often result in the death of the subject. While not typically posing a threat to life, non-malignant tumors can impose severe restrictions on normal physiological function.
Tumors are typically treated by surgical removal, radiation, and/or chemotherapy. Surgery is the oldest effective form of tumor therapy and can often result in a complete cure, depending on the type and nature of the tumor. Many tumors, however, occur in locations and/or number that make surgery impossible or impractical. Also, surgical debulking (the removal of the tumor) is not guaranteed to remove all abnormal cells, particularly in the case of tumors located in the brain where maximum preservation of normal tissue is desired. These abnormal cells remaining after surgery pose an increased risk of tumor re-growth and/or metastasis.
Radiation therapy is often used as an adjunct to surgery. Various types of radiation, both from external and implanted sources, have been used with some success. Low linear-energy-transfer (LET) sources, such as beta particles and gamma rays, require the presence of oxygen for their pharmacologic activity. Many tumors, however, are hypoxic (have reduced oxygen content) due to reduced collateral blood vessel growth into the tumor interstitia, limiting the effectiveness of low LET sources and requiring repeated treatments over extended periods of time to produce any significant reduction in tumor cells.
Brachytherapy using an implantable neutron emitting source has been used as an alternative to external radiation beams. Most of the neutron-emitting isotopes are unsuitable for brachytherapy, however, because of short half-lives or low specific neutron emission rates (i.e. neutrons per sec per gram). The transplutonium radioactive isotope californium-252 (252Cf) is an exception because it has a fairly long half-life of 2.6 years and a specific neutron emission rate of 2.34xc3x971012 neutrons per sec per gram. The neutrons emitted from 252Cf have an average energy of 2.3 MeV, which is a high LET and proven to be effective against hypoxic tumors. Brachytherapy techniques are described in detail in Applicant""s co-pending U.S. patent application Ser. No. 09/394,234, entitled xe2x80x9cMethods for Treating Solid Tumors Using Neutron Therapy,xe2x80x9d filed Sep. 13, 1999 and in U.S. patent application Ser. No. 09/395,324, entitled xe2x80x9cNeutron Brachytherapy Device and Method,xe2x80x9d filed Sep. 13, 1999, in the name of Applicant and another inventor, which are both incorporated herein by reference.
Generally, conventional thin wall tubing catheters can be utilized in the brachytherapy process, but are not desirable because the thin wall tubing of the catheters may become kinked due to handling and may even collapse during usage. Kinks reduce the effectiveness of the therapy because the radiation source may become trapped within the patient so that the patient receives an unwanted dose of radiation. Further, metal reinforced catheters cannot generally be utilized in brachytherapy techniques since the metal layers normally attenuate the conventional radiation (i.e. x-ray, gamma and beta).
Additionally, conventional catheter designs utilize a connector to couple the catheter to the afterloader. One such connector is a tapered Leur connector. The Leur connector couples to its mating part via a clockwise/counterclockwise rotating relationship. However, this rotating relationship is undesirable because the catheter may change positions while inserted in a patient""s body or could become disengaged by the rotation necessary to lock the catheter to the connector.
Accordingly, there is a need in the art for catheters that can be used for brachytherapy and other medical procedures that reduce the occurrence of collapse and kinking during usage. It is to these ends that the present invention is directed.
In accordance with the invention, A reinforced catheter is provided comprising an inner layer forming a catheter body, the body having a distal end and a proximal end, the distal end having a closed tip end, a middle reinforcing layer extending over the first inner layer to the distal end and an outer layer extending over the middle reinforcing layer.
In an alternative embodiment, a reinforced catheter is provided comprising an inner layer forming a catheter body, the body having a distal end and a proximal end, the distal end having a closed tip end, a middle reinforcing layer extending over the first inner layer to the distal end, the middle reinforcing layer cooperating with the inner layer to reduce the kinking of the inner layer and an outer layer extending over the middle reinforcing layer to seal the reinforced catheter body and to provide a surface coating for the catheter so that the catheter is capable of being easily guided into a patient.
In still another embodiment, a reinforced catheter is provided comprising an inner layer forming a catheter body, the body having a first end and a second end, the first end being closed to form a tip end, a middle reinforcing layer over the inner layer, the middle reinforcing layer extending adjacent to the tip end and an outer layer over the middle reinforcing layer, the outer layer extending to and covering the tip end such that a first portion of the catheter is characterized by a first thickness formed of the inner, middle and outer layers and a second portion of the catheter is characterized by a second thickness formed of the inner and outer layers.
Additionally, a connector for coupling a catheter to an extension tube or afterloader is provided comprising a first half having a housing with at least one pair of opposing cutout portions of a first depth provided thereon, a second half slidably connectable with the first half and a biasing means for securing the second half within the housing.
In an alternative embodiment, a connector for coupling a catheter to an extension tube or afterloader is provided comprising a first half having a housing with at least one pair of opposing cutout portions of a first depth provided thereon and a second half slidably connectable with the first half, the second half having an inner member and an outer member configured to slide relative to the inner member, the inner member having at least one pair of opposing tab portions provided thereon, the tab portions configured to protrude through the outer member such that when the first half and the second half are mated, the tab portions engage the cutout portions in the housing to secure the first half and the second half.
Additionally, a catheter system is provided comprising a reinforced catheter, including an inner layer forming a catheter body, the body having a distal end and a proximal end, the distal end having a closed tip end, a middle reinforcing layer extending over the first inner layer to the distal end and an outer layer extending over the middle reinforcing layer and a connector for coupling a catheter to an extension tube or afterloader, the connector including a first half having a housing with at least one pair of opposing cutout portions of a first depth provided thereon, a second half slidably connectable with the first half and a biasing means for securing the second half within the housing.
Additionally, a catheter system is provided comprising a reinforced catheter having an inner layer forming a catheter body, the body having a first end and a second end, the first end being closed to form a tip end, the tip end configured to house a radiation source; a middle reinforcing layer over said inner layer extending to the tip end; and a third outer layer over the middle reinforcing layer and a connector for coupling the second end to an extension tubing end, the second end being flared to form a funnel shape configured to provide for strain relief and to minimize mismatch of lumens when the catheter body is coupled with the connector, the connector having a first half, the first half having a housing with at least one pair of opposing cutout portions of a first depth provided therein; and a biasing means for securing the second half within the housing such that the biasing means and the second end of the catheter body are concentrically located; and a second half slidably connectable with the first half, the second half having an inner member with at least one pair of opposing tab portions are provided thereon and an outer member configured to slide relative to the inner member, the tab portions configured to protrude through the outer member such that when the first half and the second half are mated, the tab portions engage the cutout portions in the housing to secure the first half and the second half, the tab portions configured to not protrude beyond the first depth of the opposing cutout portions.
A method for performing a surgical procedure on a patient is also provided comprising inserting a reinforced catheter into the body of the patient, the reinforced catheter including an inner layer forming a catheter body, the body having a distal end and a proximal end, the distal end having a closed tip end, a middle reinforcing layer extending over the first inner layer to the distal end and an outer layer extending over the middle reinforcing layer.
Advantageously, kinking in a catheter body will be unlikely to occur as a result of the reinforced catheter body. Also, when mated, the connector will be unlikely to disengage the catheter and extension tubing due to the operation of opposing tab and cutout portions that create a locking mechanism. Therefore, a suitable catheter and connector may be utilized during surgical procedures without endangering a patient.